Continuous development of telecommunications services has increasingly fueled the demand for network sharing. The network sharing may be a sharing on a radio side, or may be a sharing on a core network side. The network sharing not only provides a cost-effective operating mode to traditional operators who are exploiting new business, but also provides manufacturers in other vertical industries, or some large-size enterprises, groups and VIP (very important person) users with opportunities to meet a special requirement or fulfill a new service by taking advantage of an existing network. However, there are more and more customers demanding to use their own core network devices to operate self-operated services, so as to improve an operating speed and enhance security.
For example, a large scale M2M (machine to machine) manufacturer may express a preference to share a radio infrastructure in an existing cellular network while operating a self-operated service by using a dedicated core network device established by itself; a VIP customer may hope to establish a separate core network to satisfy a demand of the VIP customer for high quality communication, or a mobile virtual network operator (MVNO) may deploy a core network device to operate a self-operated service.
However, a new problem which accompanies the foregoing demands is how to select a specific core network device for access by a terminal user of the foregoing customer who deploys a core network device by itself.
According to a practice in the prior art, a terminal user initiates an attach request to a network, and an RAN (Residential Access Network) side selects an MME (mobility management entity) according to a random number or according to weighting coefficients of MMEs in an MME pool to perform access.
It can be seen that in a method in the prior art, as shown in FIG. 1, a dedicated MME for a user should be an MME2, but according to an existing selection algorithm, an eNodeB (evolved NodeB) may select an MME1. Because the MME1 is not configured as a network element serving the terminal user, the MME1 may reject attach by the user terminal, thereby causing an access failure of the user, and greatly affecting a service process of the user.